Recent developments in the computer and computer networking industries have spawned an ever increasing demand for fast access to large amounts of data relating to objects such as images, audio, and documents. Dramatic increases in both data storage capacity and computer processing speed have allowed computer applications to process and store greater amounts of data facilitating data content rich with multi-media. Similar advances in computer networking have lead to dramatic increases in both communications bandwidth and the breadth of network access. With these advances, vast amounts of information are routinely shared among computers supporting web-based and other networked applications.
Typically, a host computer is connected to a storage device, such as a hard disk drive or a file server, having a memory that holds the information in the form of objects. When the host computer receives a request for a data object, the storage device is queried and the object is retrieved from the storage device and transferred to the host computer. To reduce a delay involved in accessing the object from the storage device, a cache is often used on the host computer. The cache typically includes a smaller memory used to store the most frequently requested objects from the storage device. The cached objects are more quickly accessible than objects stored within the larger storage device. Therefore, subsequent requests for objects that have been cached can be responded to quickly directly from the cache, without the need to access the storage device.
A typical cache includes binary logic functioning when the cache receives a request for an object to determine if the object is available in the cache. If the object is available in the cache, the cached object is used to respond to the request. If the object is not available in the cache, the object request is responded to by retrieving the object from the larger storage device. If the storage device is connected to the requesting processor through a shared communications bus, there will likely be delays to retrieve the object due to the bandwidth of the bus, competition from other devices connected to the bus, and additional instructions necessary to communicate the object request to the storage device and the object delivery to the requestor. This delay will likely be even greater if the storage device, such as a web server, is remotely located and connected by a communication link such as the World Wide Web.